Document WO 2013/038012 describes a method for assembling a box structure, which uses gluing for the assembly. This assembly method, known as fastener-free assembly, is entirely satisfactory and particularly makes it possible to increase productivity as compared to solutions of the prior art that chiefly use riveting. This type of assembly using gluing allows the assembled structure to carry away the service forces to which it is subjected. For example, when the assembly is used to make a wing box that is subjected to torsion loads, the interfaces glued in this way can carry away the forces between the skin and the understructure in nominal operating conditions. However, for aeronautics applications, the structure must be tolerant to damage, and in such a configuration, when a glued interface is damaged, it can no longer transmit forces in a shearing direction parallel to the interface, and does not offer an alternative path for the propagation of the flow of force. Thus, according to the prior art, assemblies that are vital for the safety of the aircraft, such as wing boxes, continue to be assembled by riveting even if the elementary parts making them up are made of composite materials. In addition to the adverse effect on the mass of the assembly made in that way, the installation of fasteners leads to a number of drawbacks in terms of productivity and the risk of scraps. Thus, the installation of each fastener requires drilling when the elementary parts are pre-assembled, inspection and, depending on the case, protection from the risk of sparking if it opens into an area containing fuel. Each of these operations is likely to generate defects; several thousands of fasteners are installed on a structure like a wing box, and some of the fasteners are installed with access to only one side of the skin, or with reduced access to the other face, because the box structure is closed by said skin.
Document EP 2 703 283 describes a composite structure of an aircraft wing assembled by gluing.
Document FR 2 576 279 describes the structure of a wing made of composite material and comprising the connection of a spar to the skins that make up the aerodynamic surfaces by means of brackets.
Document U.S. Pat. No. 5,847,375 describes a method for assembling a structure of stiffeners made of composite material with a thermoplastic matrix using welding.